System of control



A. H. CANDEE.

SYSTEM OF CONTROL.

APPLICATION FILED ocr. 30. ms.

INVENTOR Andrew H Cafldze A.TTORNEY WITNESSES: H} X KM UNITED STATESPATENT OFFICE.

ANDREW H. CANDEE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTING-HOUSE ELECTRIC & MANUFACTURING COMPANY, CORPORATION OF PENN- SYLVANIA.

SYSTEM OF CONTROL.

To all whom it may concern:

Be it known that I, ANDREW H. CANDEE, a citizen of the United States anda resident of Pittsburgh, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in Systems ofControl, of which the following is a specification.

- My invention relates to control systems and particularly 'to thecontrol of storagebattery locomotives and the like.

One object of my invention is to provide a system that is adapted tofulfil all the functions of previous systems of the aboveindicatedcharacter without requiring the use of as many switches, wherebyreductions in first cost and maintenance and in space and Weightrequirements are efi'ected. Another object of my invention is to soconnect a resistor in'circuit, in systems of the type underconsideration, that not only may a certain number of switches beeliminated, but the resistor may also be employed forshunting the motorfield winding to assist in providing an additional accelerating step.

In the construction of control systems for mining'locomotives' and thelike, it is imperative to reduce the space requirements to a minimum, byreason of the narrow passages through which the locomotive must run. Thepresent invention fulfils this requirement in a. material degree and,moreover, also, eifects a decrease in the cost of the system, sinceaa'certain number of circuit switches or equivalent drum-controller contactmembers are eliminated with respect to previous systems of this generalclass.

My invention may best be understood by reference to the accompanying:drawing, wherein Figure 1 is a diagrammatic view of the main circuitsof a" system ofcontrol embodying my invention; Fig.2 is a sequence chartof well-known form, indicating the preferred order of. operation oftheIvarious switches that are illustratedinFig. 1; and Fig. 3 to Fig.13, inclusive, are simplified diagramatic views illustrating the circuitconnections that. are obtained during various operating periods of thecontrol system. 1

Inasmuch as it is within the province of any engineer skilled in thecontrol art to readily devise a master. controller, or the Specificationof Letters Patent. .Patent d A 16 1 2 Application filed October so,1918. Serial No. 260,281.

equivalent, for manually governing the various switches in the sequenceindicated in Fig. 2, I have not deemed it necessary to illustrate anddescribe any such master controller, but it is believed that thesequence chart, together with the numerous simplified;d1agrams, willserve to fully disclose my invention.

Referring to Fig. 1 of the drawing, the system shown comprisesa suitablesource of energy, such asa storage battery B that is carriedupon thelocomotive; a plurality of propelling motors, one of which has acommutator-type armature 3 and an exciting field winding having two setsof distinct portlons or sections 4 and 5, and the other or whlch hassimilar armature and field windings 6, 7 and 8, respectively; aplurality of resistors 9 and 10, each of which is used for the doublepurpose of varying the armature-circuit resistance and shunting thefield'vvindings; a plurality of unit switches, or'the equivalent, F1, FF1, F2, FF2, R1, RRl, R2 and BB2, the first four of which are employed toefi'ect forwardoperation of the locomotive, while the last four areutilized to produce reverse running; and a plurality ofcircuit-adjusting switches S, B, R

RR, 1, 11, 2, 22, P1, P2 and P3. Although, for the sake of simplicityand clearness, only two field-winding sections are shown associatechwitheach motor, it should be understood that the actual preferredconstruction embodies four polar projections severally provided with twoseparate portions that respectively constitute a part'of the illustratedwindings 4 and 5, for example. a 1 Assuming that it is desired to effectfor ward operation of the locomotive, the master controller (not shown),or its equivalent, is actuated to its first step or position a, wherebyswitches S, B,F1, FFl, F2 and FF2 are closed, as indicated by the firstline of the sequence chart, Fig. 2.

A circuit is thereby established from the positive terminal of thebattery B through conductors 13 and 14:, switches S and F1, armature 3,switch FFl, conductor 15, fieldwinding section 4, resistor 9, conductor16, field-winding section 5, conductor 17, switch F2, armature 6, switchFF2, field-winding section 8, conductor 18, resistor 10, fieldwindingsection 7, switch B- and conduc-.

tor 19 to the negative battery terminal. The straight series connectionof all armature and field windings with the resistors 9 and 10 that isillustrated in Fig. 3 is thus effected to start the motors intooperation.

In position b of the above-mentioned master controller, switch R isclosed to shortcircuit the resistor 9, as shown in Fig. 4, while, instep c. the switch RE is also closed, as illustrated in Fig. 5. toshortcircuit the other resistor 10. In this way, a predetermined degreeof acceleration is imparted to the propelling motors.

As the controller is moved through transition positions (Z and e,switches 1 and 2 are closed. and the switches R and RR are then openedto short-circuit the resistors 9 and 10 together with theseries-connected fieldwinding sections d and 8 of the respective motors,as illustrated in Fig. 6.

In step f. switches 11 and 22 are closed to connect the pairs offield-winding sections 4 and 7, and 5 and 8, respectively, in parallelrelation to the same resistors 9 and 10, as shown in Fig. 7. Thefield-shunting connections described above serve to effect furtheracceleration of the propelling motors in accordance with well-knownprinciples. It should be noted, however, that the use of the sameresistor for shunting both field-winding sections of one motor, whichresistor is that initially used for excluding resistance from the maincircuit, effects a certain economy in cost and weight of the controlapparatus. In particular, one switch is dispensed with by shunting theresistor across the field-winding sect-ions rather than opencircuitingthe resistor. Since, in all practical railway series-motor cases, theresistor would have a relatively high resistance compared with that ofthe field-winding sections, it follows that the increase in speed thatis secured by step 7 is almost the same as that obtained by a plainchangeover of the field winding sections from series to parallelrelation.

The system is now in readiness for transition to the parallel relationof the motors. In transition positions 9, h and 2', the controller firstreleases the switches 2 and 22 to produce the straight series connectionof the armature 6 and its field-winding sections with the resistor 10,as illustrated in F 8, next closes the switches P1 and P2, thusproviding a direct connection between conductors 13 and 17 to shunt theentire motor having the armature 3, as shown in Fig. 9, and finallyopens switches S, 1 and 11, while closing switch R, to temporarilydisconnect the shunted motor from circuit and, at the same time,short-circuit the resistor 9, as illustrated in Fig. 10. It will beappreciated that, if desired, a single switch of sufiicientcurrentcarrying capacity may be substituted for the two light-weightswitches P1 and P2, which are here used for special engineering reasons:namely, to afford interchangeability of all the illustrated switches,with the consequent advantages.

In the next running position j, switches "0 BR and P3 are closed, thusconnecting the temporarily short-circuited terminal of the armature 3 tothe negative battery terminal and concurrently short-circuiting theresistor 10, as shown in Fig. 11. The motors are 7 thus connected infull-parallel relation across the battery terminals, with fullfield-winding excitation.

In transition positions and Z, switches 1 and 2 are first closed againand then switches It and RR are opened to shunt the resistors 9 and 10together with the fieldwinding sections 4- and S, as illustrated in Fig.12.

In the final running position m, switches 11 and 22 are closed to againshunt the pairs of field-winding sections across the resistors 9 and 11,respectively, thus producing the weak-field connections, with the motorsconnectod in parallel relation, as shown in Fig. 13.

It will be seen that I have thus provided a system wherein a number ofresistor-shorteircuiting switches are eliminated by reason of thepermanent connection of resistors between the field-winding sections ofeach motor, and the cost and space and weight requirements of the systemare still further reduced by utilizing such accelerating resistors tosubsequently shunt the field-winding sections. The ohmi: value of eachresistor, in all practical cases, will be relatively high compared tothe resistance of the field windings, being at least thirty times theresistance of the field windings 5 when connected in parallel relation.Consequently, the losses in the resistors, when used for thefield-shunting purpose, will be relatively small.

I do not wish to be restricted to the speciliccircuit connections orarrangements of parts herein set forth, as various modifications thereofmay be made without departing from the spirit and scope of my invention.I desire, therefore, that only such limitations shall be imposed as areindicated in the appended claims.

I claim as my invention:

1. The method of accelerating an electric motor having an armature and aplurality of field-winding sections in conjunction with a resistorpermanently connected intermediate said sections that consists inshortcircuiting said resistor, short-circuiting one field-windingsection together with said re- 12 sistor, and shunting the resistoracross both field-winding sections.

2. In a system of control, the combination with a dynamo-electricmachine having an armature and a twosection field winding,

of a resistor permanently connected intermediate said sections, andthree switches respectively connected across the resistor alone andacross the resistor together With the one or the other field-Windingsection.

3. In a system of control, the combination with a dynamo-electricmachine having an armature and a plurality of field-winding sections, ofa resistor permanently connected 10 intermediate said sections, meansfor exeluding said resistor from circuit, means for short-circuiting onefield-Winding section together With said resistor, and means forshunting the resistor across both field-winding sections.

In testimony whereof, I have hereunto subscribed my name this 26th dayof Oct., 1918.

ANDREW H. GANDEE.

